A christmas carol has a metaphor
"The streets reeked of crime"
Answer: N. Scott Momaday - who is a native American himself - finds ironic that white people claimed that they were arriving into the "new world" when in reality there were ancient civilizations already living on those lands, and this claim is one that they have continued to sustain up to this day.
When Europeans arrived in 1492, there were very large Indian populations scattered all across America with a rich history and culture, an element that vastly defers the logic of the discovery of a "new world".
D is a chronological event. The War Memorial was created where, how and maybe why. The maybe why is only about why Washington was chosen.
B again is recounting exactly how the peace was brought about in korea in the 1950s. It's not a positional paper.
A is not a position although it could be made into one. This question is a bit ambiguous and you are forced to choose between A and C. I would pick C because it is a position. No matter what else is relayed, the thing you must determine is that the Dental Association has a position: prevention.
A cannot be so easily dealt with. The problem is that it has a position, but it looks like it does not have any kind of resolution. It's intent is to show that antibiotics have an effect on the food chain. If it said a "good" effect or a "bad" effect, it would be a shoo in.
Answer C <<<<< But don't be surprised if it is A nevertheless.
The answers are a,b, and d